Tetraazanaphthalenes nucleophilic substitution

The two most reactive types of derivatives are expected to be the 4-Le-l,3,6,8- and 4-Le-l,2,3,6-tetraazanaphthalenes 456 and 457. Of the twenty-two possible ring systems, ten are known in aromatic form, and nucleophilic substitution has been carried out on only four of these. Covalent hydration has been observed in the pteri-dines and in 1,4,6,8-tetraazanaphthalenes. 

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